The present application is based on Japanese Patent Applications No. 2001-28019 and No. 2001-132050, the entire contents of which are incorporated herein by reference.
The present invention relates to a head protecting air bag device, and particularly to a head protecting air bag device having a bag body which expands and develops in the shape of a curtain in the longitudinal direction of a vehicle body on a cabin side.
Conventionally, in a head protecting air bag device having a bag body which expands and develops in the shape of a curtain in the longitudinal direction of a vehicle body on a cabin side, as disclosed in Japanese Patent Publication JP-A-2000-127886, a cloth-made inner tube in which gas outlet holes are formed at the predetermined distance in the forward and backward direction of the vehicle body is provided in a gas passage that is formed at the upper portions of a front seat expansion room and a rear seat expansion room of the bag body and extends axially in the forward and backward direction of the vehicle body, and expansion gas is supplied uniformly to each expansion room of the bag body. In such the head protecting air bag device, since the cloth-made inner tube provided in the bag body can be folded simultaneously with the bag body, this device is advantageous to reduce a housing space.
However, in this head protecting air bag device, when the bag body expands and develops, the inner tube folded must be spread by gas pressure. Further, in the vicinity of a gas ejection port of an inflator, the diffusion pressure of expansion gas is strong. Therefore, the inner pressure of the inner tube in the vicinity of the gas ejection port of the inflator becomes temporarily high very much, so that the inner tube is frequently damaged.
An object of the invention is, in view of the above facts, to obtain a heat protecting air bag device in which damaging of an inner tube in the vicinity of a gas ejection port in an inflator can be reduced.
According to the first aspect of the invention, there is provided a head protecting air bag device comprising: a bag body forming at least one expansion room and a gas passage extending in the longitudinal direction of a vehicle body communicating to the expansion room; an inflator which ejects expansion gas in the bag body; a flexible inner tube provided in the gas passage and for supplying the expansion gas into the expansion room; and a pipe coupled to a gas ejection port of the inflator and extending in an axial direction of the inner tube, a leading end of the pipe protruding into the inner tube.
Accordingly, when the inflator operates, the expansion gas from the inflator is supplied through a gas outlet hole of the inner tube to the expansion rooms of the bag body, and the bag body develops in the shape of a curtain thereby to protect the head of the occupant. At this time, the pipe having the small length and the small diameter provided in the inner tube rectifies the expansion gas ejected from the gas ejection port of the inflator. As a result, the inner tube folded is easily spread by the expansion gas, and the diffusion of the expansion gas becomes weaker at the outlet of the pipe than at the gas ejection port of the inflator. Therefore, since it is possible to prevent the inner pressure of the inner tube in the vicinity of the gas ejection port of the inflator from temporarily becoming high very much, damaging of the inner tube can be reduced. Further, since the pipe is short, the convenience of housing the bag body in the device is not greatly worsened.
According to the second aspect of the invention, in the head protecting air bag device according to the first aspect, there is provided a deflecting portion which deflects the ejecting direction of the expansion gas ejecting from a leading end of the pipe to the opposite side to a sewed portion of the inner tube.
Accordingly, in addition to the contents of the first aspect, since the sewed portion side of the inner tube is weak in tear strength due to the existence of machine stitches, the ejecting direction of the expansion gas ejecting from the leading end of the pipe is deflected by the deflecting portion to the opposite side to the sewed portion of the inner tube, whereby the amount of the gas ejection to the sewed portion is suppressed. As a result, damaging on the sewed portion side that is weak in the tear strength can be reduced effectively.
According to the third aspect of the invention, in the head protecting air bag device according to the second aspect, the deflecting portion is the leading end of the pipe cut slantingly.
Accordingly, in addition to the contents of the second aspect, by only such a small modification that the leading end of the pipe is cut slantingly, damaging on the sewed portion side that is weak in the tear strength can be reduced effectively.
According to the fourth aspect of the invention, in the head protecting air bag device according to the first aspect, an axis of the inflator in the mounting position is offset with respect to an axis of the leading end of the pipe in vertical direction, and a bending portion is formed at a part of the pipe that is near the gas ejection port of the inflator.
Accordingly, in addition to the contents of the first aspect, since the axis of the inflator in the mounting position is offset with respect to the axis of the pipe in vertical direction and their axes are not on a line, in case that the pipe is bent halfway, a loss in pressure becomes large, so that this device is disadvantageous to secure an expansion development time of the bag body and the inner pressure in the bag body. Therefore, the bending portion is formed at a part of the pipe that is near the gas ejection port of the inflator, whereby the loss in pressure caused by bending of the pipe can be reduced.
According to the fifth aspect of the invention, in a head protecting air bag device comprising an inflator which ejects expansion gas in a bag body, a gas passage which communicates to expansion rooms for protecting a head of an occupant and the upsides of the expansion rooms and extends in the longitudinal direction of a vehicle body, and a flexible inner tube, which is provided in the gas passage and supplies the expansion gas into the expansion rooms, there is provided a high-voltage resistant flexible tube having a small length and a small diameter is provided, which protrudes axially from the inflator into the inner tube.
Accordingly, when the inflator operates, the expansion gas from the inflator is supplied through a gas outlet hole of the inner tube to the expansion rooms of the bag body, and the bag body develops in the shape of a curtain thereby to protect the head of the occupant. At this time, the high-voltage resistant flexible tube having the small length and the small diameter, which protrudes axially from the inflator into the inner tube, rectifies the expansion gas ejected from the gas ejection port of the inflator. As a result, the inner tube folded by the expansion gas is easily spread, and the diffusion of the expansion gas becomes weaker at the outlet of the high-voltage resistant flexible tube than at the gas ejection port of the inflator. Therefore, since it is possible to prevent the inner pressure of the inner tube in the vicinity of the gas ejection port of the inflator from temporarily becoming high very much, damaging of the inner tube can be reduced. Further, since the high-voltage resistant flexible tube is used, it can be folded up in flat, so that deterioration of convenience of housing the bag body in the device can be further suppressed.
According to the sixth aspect of the invention, in a head protecting air bag device comprising an inflator which ejects expansion gas in a bag body, a gas passage which communicates to expansion rooms for protecting a head of an occupant and the upsides of the expansion rooms and extends in the longitudinal direction of a vehicle body, and a flexible inner tube, which is provided in the gas passage and supplies the expansion gas into the expansion rooms, there is provided a high-voltage resistant flexible tube having a small length and a small diameter is provided, which protrudes axially from the inflator into the gas passage in the bag body, and the inner tube is covered with the high-voltage resistant flexible tube so that the inner tube is narrowed.
Accordingly, when the inflator operates, the expansion gas from the inflator is supplied through a gas outlet hole of the inner tube to the expansion rooms of the bag body, and the bag body develops in the shape of a curtain thereby to protect the head of the occupant. At this time, the high-voltage resistant flexible tube having the small length and the small diameter, which protrudes axially from the inflator into the inner tube, rectifies the expansion gas ejected from the gas ejection port of the inflator. As a result, the inner tube folded by the expansion gas is easily spread, and the diffusion of the expansion gas becomes weaker at the outlet of the high-voltage resistant flexible tube than at the gas ejection port of the inflator. Therefore, since it is possible to prevent the inner pressure of the inner tube in the vicinity of the gas ejection port of the inflator from temporarily becoming high very much, damaging of the inner tube can be reduced. Further, since the high-voltage resistant flexible tube is used, it can be folded up in flat, so that deterioration of the convenience of housing the bag body in the device can be further suppressed. Further, since the inner tube is covered with the high-voltage resistant flexible tube so that the inner tube is narrowed, the high-voltage resistant flexible tube is not directly exposed to the expansion gas by the inner tube located inside. As a result, since high-temperature resistance of the high-voltage resistant flexible tube can be lowered, a cost can be reduced.
According to the seventh aspect of the invention, in the head protecting air bag device according to any of the first to sixth aspects, an inner diameter of the pipe having the small length and the small-diameter or the high-voltage resistant flexible tube is smaller than an outer diameter of the ejection part of the inflator, and the pipe or the tube does not extend over a gas outlet hole in the inner tube that is nearest to the inflator.
Accordingly, in addition to the contents of any of the first to sixth aspects, the expansion gas can be reliably blown also into the gas outlet hole in the inner tube that is nearest to the inflator.